Here's a video tutorial discusses how to make 3d sketches as a base to then paint on top of when creating digital imagery. It discusses the 5 most important things to work out in your 3d sketch: Composition, Camera, Perspective, Lighting, And Texture. The painting is from my forthcoming Concept Art book "Inc". A lowres version of this video is available on my soulburn3d youtube channel, but this one is higher quality and downloadable.
Visit http://www.neilblevins.com for examples of my art, other educational materials, and cg tools.